About the sound your MacBook or MacBook Pro makes when you plug it in

MacBook (2015 and later) and MacBook Pro (2016 and later) make a tone when you connect them to power. This lets you know that your computer recognized the power adapter.

If your Mac is turned off when you connect the adapter, your keyboard and trackpad won’t become active until after you hear the tone. After the tone, you can press the power key to power up your MacBook or MacBook Pro.

It's best to use the Apple AC power adapter that came with your computer.